This relates generally to imaging devices, and more particularly, to imaging devices having dark pixels.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an image sensor includes an array of image pixels arranged in pixel rows and pixel columns. Circuitry may be coupled to each pixel column for reading out image signals from the image pixels.
Typical image pixels contain a photodiode for generating charge in response to incident light. Image pixels may also include a charge storage region for storing charge that is generated in the photodiode. Image sensors can operate using a global shutter or a rolling shutter scheme. In a global shutter, every pixel in the image sensor may simultaneously capture an image, whereas in a rolling shutter each row of pixels may sequentially capture an image.
Some image sensors may include dark pixels to help correct for pixel noise. The dark pixels may include photodiodes that are shielded to prevent the dark pixel photodiodes from being exposed to incident light, ensuring that any generated charge is merely noise. Although helpful for noise correction, dark pixels may take up valuable area in the image sensor.
It would therefore be desirable to be able to provide improved arrangements for dark pixels in image sensors.